If you have reached a plateau, it is only in the area of water loss, not fat loss. Dr. Shelton has taught that our basal metabolic rate is reduced by 25-40% gradually over a long fast, never that it would be reduced by 80% in one day. If your goal is to continue losing a lot more water weight, then you have a big problem here because that will not happen, but if it is to continue losing fat in an only slightly diminishing amount each day then you are in good shape.
Your body burned almost exactly as much fat in day 11 as it did it day 10 because it required that much fuel and had no choice. For example, if you burned .6 pound of fat on day 10, you would have burned about .58 or .59 on day 11 (note that this assumes an equal amount of exercise and other activity). I do believe also that your body held onto a bit more water than it released today and that this fluctuation contributed to your reduced weight loss on this day, something that could be entirely different tomorrow.
Sorry if this is bad news but i hope you will rejoice in the fact that you are doing something amazingly beneficial for your body and that you can absolutely continue losing more and more fat with the right nutritional and exercise plan once your fast is completed.